function s1_read_last_two_bytes_of_a_mbr_backup_file(){
      local file_Path=$1
      local last_bytes=$(tail -c 2 "$file_path" | od -A n -t x1 | tr -d ' \n')
      if [ "$last_bytes" = "55aa" ];then
            echo "YES"
      else
            echo "NO"
      fi
}

function s2_read_mbr_partition_table_info(){
      for i in {0..3};do
            offset=$((446 + i * 16))
            start_sector=$(dd if="$1" bs=1 skip=$((offset + 8)) count= 4 2>/dev/null | od -t u4 -An | tr -d ' \n')
             if ! [[ $start_sector =~ ^[0-9]+$ ]];then
                   continue
             fi
             if [ "$start_sector" -eq 0 ];then
                   continue
             fi
             size_sector=$(dd if="$1" bs=1 skip=$((offset + 12)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
             end_sector=$((start_sector + size_sector - 1))
             echo "$start_sector $end_sector"
       done
}

function s3_parse_partition_info(){
      fdisk_output=$(cat)
      disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
      disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}')
      physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
      first_partition_start_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $3}')
      first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $4}')
      first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $8}')
      echo "disk size in bytes:$disk_size_bytes"
      echo "disk size in sectors:$disk_size_sectors"
      echo "physical sector size in bytes:$physical_sector_size"
      echo "first partition start sector id:$first_partition_start_sector"
      echo "first partition end sector id:$first_partition_end_sector"
      echo "first partition type:$first_partition_type"
}

function s4_run_passwd_as_plain_user_and_get_status(){
      oversleeping_path=$(which oversleeping)
      chown root "$oversleeping_path"
      chmod 755 "$oversleeping_path"
      oversleeping &
      ps -o uid,euid,ruid -C oversleeping | awk 'NR>1 {print $1","$2","$3}' 
}

function s5_add_a_scheduled_task(){
      touch $HOME/test_crontab;
      echo "*/5 * * * * date +\%Y\%m\%d_\%H\%M\%S >> $HOME/test_crontab" | crontab -
}
